For example, Japanese Patent Publication No. 4,902,796 discloses a machine for successively making plastic bags. The machine includes a longitudinal heater, a cross heater and a cutter by which plastic films are heat sealed with each other longitudinally and widthwise thereof and cross cut widthwise, to successively make plastic bags. The plastic bags are then discharged successively and horizontally. In this case, it is required to stack the plastic bags to achieve a quorum and feed the plastic bags whenever stacking them.
Japanese Laid-Open Patent publication No. 189,455-2004 discloses an apparatus to fulfill the requirement. In the apparatus of the publication, the plastic bags are discharged successively by nip rollers after making the plastic bags. A shutter plate is disposed above a conveyor so that the plastic bags should collide against the shutter plate to fall onto the conveyor after being discharged successively, for stacking the plastic bags on the conveyor. The apparatus is arranged to feed the plastic bags by the conveyor after stacking the plastic bags to achieve a quorum.
However, the apparatus is problematic in that until feeding the plastic bags after stacking, coming bags are not allowable to fall onto the conveyor for stacking. The machine has therefore to be stopped temporarily so that the coming bags will not be discharged temporarily. The plastic bags cannot be discharged continuously. The machine can therefore not continuously make plastic bags.
In order to overcome the problem, catcher bars should be disposed above the conveyor and opposed to the discharge position. The catcher bars extend in the discharge direction of plastic bags. The catcher bars are arranged and spaced from each other in a lateral direction. It should be understood that the lateral direction denotes a horizontal direction normal to the discharge direction. In addition, shutter bars should be substituted for the shutter plate and disposed between the discharge position and the catcher bars. The shutter bars extend vertically. The shutter bars are also arranged and spaced from each other in the lateral direction. The plastic bags can therefore collide against the shutter bars to fall onto the conveyor after being discharged successively, for stacking the plastic bags on the conveyor. In addition, the catcher bars are moved longitudinally thereof to pass between the shutter bars and protrude toward the discharge position so that coming bags should be received on the catcher bars after stacking the plastic bags. The catcher bars are then moved reversely to be returned to the original position so that the coming bags should fall onto the conveyor after feeding the plastic bag by the conveyor. Subsequently, the plastic bags collide against the shutter bars to fall onto the conveyor for stacking. The plastic bags can therefore be discharged continuously. The machine can continuously make the plastic bags.
In this case, in the discharge direction of plastic bags, the catcher bars must protrude downstream thereof when being returned to the original position. In addition, the catcher bars have to be held and moved by a catcher drive at the downstream end thereof, taking a large space. The catcher bars must be heavy, taking a large energy when being moved. In a machine for making the plastic bags at high speed, the catcher bars have to be moved and returned at high speed to protrude downstream thereof at high speed, resulting in a problem of safety of operator.
The apparatus may be applied to sheet products other than the plastic bags to stack and feed them discharged successively from a discharge position. However, the fact remains that the apparatus has the problems of large space, large energy and safety.
It is therefore an object of the invention to provide an apparatus for stacking and feeding sheet products discharged successively from a discharge position, in which the sheet products can be discharged continuously without involving the problems of large space, large energy and safety.